Slaven Bilic is a man just as comfortable strumming his beloved red Gibson Explorer guitar as he is striding down the touchline. The 46-year-old former Croatia international has spoken before of how music is an essential part of his management style, often asking his players to listen to inspiring songs both before and after games. Maybe it was 'I'm Forever Blowing Bubbles' that first attracted him to West Ham United.

Playing 48 matches for The Hammers during the 1996-97 season, Bilic is now returning to Upton Park as manager. It had seemed inevitable ever since chairmen David Gold and David Sullivan announced that Sam Allardyce's contract would not be renewed, especially when in a recent interview with West Ham TV Gold said: "It would be lovely to have someone with West Ham history." Yet while this rock star manager will no doubt liven up East London after the dour days of Big Sam, there is no doubt that his appointment is also a huge risk.

Gold and Sullivan will certainly be hoping that Bilic can have the same galvanising effect on this West Ham team as he did with the Croatia national side. During a successful six-year spell between 2006 and 2012 he managed to qualify for Euro 2008 top of the group, inflicting memorable home and away wins over Steve McClaren's England side. Defeating Germany 2-1 at the tournament itself, the quarter-final finish at that tournament (they lost on penalties to Turkey) remains the high point of his managerial career.

Guitar-playing Bilic likes to play inspirational music before and after gamesReuters

The only problem is that this achievement was seven years ago, and his career has hardly sparkled since. Failure to qualify for the 2010 World Cup and a group stage exit at Euro 2012 saw him leave his post as Croatia manager, with an indifferent career in club management following. He went on to take Lokomotiv Moscow to their worst position (9th) in the history of the Russian League, before successive third-place finishes in Turkey with Besiktas.

West Ham's owners clearly hope that even without Premier League experience, Bilic can have the same impact as Ronald Koeman did on Southampton last season. But for every untested foreign manager like Koeman that pays off, there are a dozen others that do not. Pepe Mel at West Brom, Felix Magath at Fulham and Ole Gunnar Solskjær at Cardiff are just a few recent examples.

While this rock star manager will no doubt liven up East London after the dour days of Big Sam, there is no doubt that his appointment is also a huge risk.

With one more season left at the Boleyn Ground before moving into the 54,000-capacity Olympic Stadium, this is a crucial moment in West Ham's history. Relegation is not an option, and say what you like about Sam Allardyce, he would have guaranteed that we stayed up for another season.

If the owners feel that Bilic is the man to take the club forward, then they must be prepared to seriously back him in the transfer market. A striker, central midfielder and right back are all necessary signings, as is holding on to Aaron Creswell.

West Ham are entering uncharted territory here and this appointment could either be a storming success or all end in tears. Music lover Bilic will need to be on song from the start if he is to enjoy this second stint with The Hammers.